Mass centering machine



Odi- 29, 1940- T. c. VAN DEGlFT MASS CENTERING MACHNE v Filed March 31, 1937 16 Sheets-Sheerl l was CCL 29. 1940- T. c. VAN DEGRIFT 2,219,795

MASS GENTERING MACHINE Filed March 51, 1937 16 Sheets-Sheet 2 L@ @omas C? Qmgyfl f5 0d. 29, l940- T. c. VAN DEGRIFT 2,219,795

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MASS CENTERING MACHNE Filed March 31, 1937 16 Sheets-Sheet 5 Oct. 29, 1940.

T. C. VAN DEGRIFT MASS CENTERING MACHNE Filed March 3l, 19257 16 Sheets-Sheet 6 Oct. 29, 1940.

T. C. VAN DEGRIFT mss CENTERING MAcHN Filed March 31, 1937 16 ShsetS-Sheet 7 III.

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MASS CENTERING MACHNE Filed March 51. 1937 16 sheets-sheet 8 Oct. 29, l940 T. c. VAN D'EGRIFT 2,219,795

MASS CENTERING MACHINE Filed March 31. 1957 16 Smets-Sheet 9 Od. 29, 1940. T. c. VAN DEGRIFT MASS CENTERING MACHINE Filed March 51, 193'? 16 Sheets-Sheet lO 0d. 29, 1940-- T. c. VAN DEGRIFT 2,219,795

MAS S CENTERING MACHINE Gct. 29, 1940. T. c. VAN DEGRIFT M ASS CENTERING MACHNE 16 Sheets-Sheet l2 Filed March 3l, 1937 Oct. 29, 1940. T. c. VAN DEGRIFT MASS CENTERING MACHINE Filed llarch 3l, y193'? 16 Sheets-Sheet 13 QQW NGN: www..

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Oct. 29, 1940. T. c. VAN DEGRIFT MASS CENTERING MACHINE Filed March 3l, 1937 16 Sheets-Sheet 14 OCL 29, 1940- T. c. VAN DEGRIFT 2,219,795

MAS S CENTERING MACHINE Filed March 5l, 1937 16 Sheets-Sheet l5 m @gw MMVW www Oct. 29, 1940. T, C, VAN DEGmr-'T 2,219,795

MASS CENTERING MACHINE Filed March 51, 1957 16 Smets-Sheet 16 wfmg;

Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE MASS CENTERING MACHINE Application March 31, 1937, Serial No. 133,994

17 Claims.

This invention relates to balancing and more particularly to a machine for determining the axis of rotating balance orV the mass center of rotating bodies, such as crankshafts and the like.

In my prior Patent 1,761,945, dated June 3, 1930, I have illustrated and described a method and apparatus for centering a rough crankshaft forging on its axis of rotating balance, instead of along an axis determined by surface symmetry as was common in the art. When the axis of 'rotating balance is thus determined, the ends of the crankshaft are drilled along this axis and all machining of the shaft is performed while the shaft is held upon this line of centers. By selecting the center line in this Way, it is found that the machined crankshaft has a low degree'of unbalance and may be within the allowablemanufacturing limits. If not Within allowable limits, the shaft may be easily balanced by removing a smallv amount of metal. While the method and apparatus disclosed in the patent has many advantages it is necessary to start and stopfthe machine a number of times to shift the forging to the center position. In the method and appa- 25 ratus comprising the subject matter of this invention, the mass axis of the shaft is located while the shaft is being rotated. Obviously, production is greatly increased over that of the prior art devices.

The specific embodiment of my invention shown in the drawings comprises a substantially perfectly balanced cradle unit mounted flexibly in horizontal position and rotated by means of an electric motor connected to one end of the cradle by means of a universal joint. Mounted on the cradle and forming a portion of the cradle unit are electric motors which, through suitable speed reducing means, drive positioning rollers adapted to shift the crankshaft within the cradle. An optical indicating means is provided to indicate the balance characteristics of the shaft. If found out of balance, the operator can readily shift the shaft within the cradle while the cradle is rotating, by means of the motors and positioning rollers. By thus shifting the shaft while it is rotating a great saving in time and labor results. In fact, the production on machines ofthe type described in this specification is approximately twice, or even more than twice, that of old type machines. After theshaft has been accurately centered, the center drill holes from which all future machine work will be located vmay be drilled before the forging is removed from the cradle. The device also comprises controls adapted to facilitate the results set forth above.

Aim

(Cl. 'i3-53) The principal object of my invention is to provide a machine for speedily and accurately locating the axis of rotating balance or the mass axis of a rotating body.

Another object of my invention is to provide an apparatus for rapidly locating the mass center of a rotating shaft and for drilling the ends thereof.

A further object of my invention is to provide a mass centering machine which comprises a substantially perfectly balanced cradle unit and means for shifting work within the cradle while the cradle and work are being rotated.

Still another object 'of my invention is to provide a means where'by the ends of the shaft may` be drilled in line with its mass axis without removing the shaft from the machine.

It is also an object of my invention to provide a control system for the several motors whereby the operation thereof may be readily controlled.

A still further object of my invention is to provide a cradle adjusting means whereby shafts of different lengths may be rapidly centered.

Other objects and advantages of my invention will become more apparent as the description proceeds. Reference isherein made to the accompanyingy drawings, forming a portion of this specification, in which two embodiments of my invention are disclosed.

Figure 1 is an elevational view of the complete machine.

Figure 2 is a longitudinal sectional view taken substantially on the line 2 2 in Figure 3.

Figure-3 is an elevational view with parts in section taken on line 3 3 in Figure 1.

Figure 4 isa detail sectional view taken on line 4 4 in Figure 3.

Figure 5 is a view on line 5 5 in Figure f1.

Figure 6 is a diagrammatic view showing a revolving mirror adapted to throw a'beam of light onto a chart to indicate balance characteristics of the rotating shaft.

Figure '7 is a view showing means for operating a locking mechanism and an air valve control mechanism for air cylinders adapted to secure the cradle and shaft in position for drilling the latter, said air valve control and locking mechanisms beingin unlocked position.

Figure 8 is a sectional view on line 8 8 in Figure 7.

Figure 9 is a longitudinal sectional view taken on line 9 9 in Figure 8.

Figure 10 is a View on line "I Hl in Figure 8 showing the control cam for the air valves which operate devices Vfor locking the cradle in position with the control cam in unlocked position.

Figure 11 is a sectional view on line lI-II in Figure 9 showing the motor drive for rotating the cradle and crankshaft therein.

Figure 12 is a sectional view on line l2-I2 in Figure 11.

Figure 13 is a sectional view on line |3-I3 in Figure 12, showing the driving means for the revolving mirror.

Figure 14 is a view of one of the end motors and the means for driving the drill.

Figure 15 is a plan view of the cradle and crankshaft centering means.

Figure 16 is a sectional view on line lli-I6 in Figure 15 showing motor driven rollers adapted to move one end of the crankshaft to accurately -position the same in the cradle.

Figure 1'1 is a detail sectional view on line |1-I1 in Figure 15 showinga means to locate the crankshaft during the operation of placing the same in the cradle. J i Figure 18 is a detail view `on line I8--l8 in Figure 15 showing a supportfor a crankshaft during the loading and unloading operation.

Figure 19 is a sectional view taken on line lil-I9 in Figure 16 showing the means for driving the positioning rollers which' move one end of the crankshaft.

Figure "20 is a detail. sectional view on line 20-20 in Figure 19.

Figure 21 -is a sectional view on line 2I-2I in Figure 19 showing a gear reduction means.

Figure 22 is an enlarged sectional view taken on line 22-22 in Figure 3 showing one end of the cradle with electrical controls applied thereto.

Figure 23 is a wiring diagram of a control circuit that may be used for controlling the `several motors.

540 Figure 24 is a view showing a modified form of cradle which may be used in cases where crankshafts of different lengths lare' to be balanced and centered.

`Fig-ure 25 is a sectional view on line 25-25 in 45 Figure 24 showing a crankshaft locating means that may be used with the cradle of Figure 24. Figure 26 is a view on line.26-26 in Figure 25 showing a safety control switch.

Figure 27 is a view on line 2 1-'21 in Figure 50 24 showing motor driven rollers which may be used to vary the position of one end of the crankshaft within the cradle.

Figure 28 is a partial sectional view taken on line 28-28 in Figure 24.

55 Figure 29 is a partial sectional view taken on line 29-29 in Figure 27 showing the motor and speed reducing means for driving the crankshaft locating rollers. l

Figure 30 is a sectional view taken on line 60 30-30 in Figure 29.

Figure 31 is a view taken on line 3I-3I in Figure 29 showing the relation of the several gears of the speed reducing means.

Figure 32 is a sectional view on line 32-32 in 65 Figure 27 showing a detail of a portion of av locking bolt and a contact carried thereby.

, Figure 33 is a partial sectional view showing one end. of the cradle illustrated in Figure 24 and electrical controls therefor.

General description a The balancing machine of one embodiment of my invention shown in the drawings comprises a horizontally disposed substantially perfectly 75 balanced cradle. indicated generally at 2, withinwhich is mounted a crankshaft 4. 'I'he cradle and crankshaft therein are rotated by means of a motor 5. Two motors 6, are mounted at either end of the cradle, rotate therewith, and are until the shaft is in balance and locate the mass center thereof. After the mass center has been determined the crankshaft may be fixed in position and the ends thereof bored by means of drills driven by motors I2. The cradle and motors are adjustably mounted on 'ways I3, which in turn are mounted on the bed I8.

Cradle end supports The ends of the cradle are flexibly supported byl similar mechanisms contained in enclosing casings 22 and 24. A detailed description of one supporting mechanism will serve also as a description of the other. In Figures 2 and 3 an arm member 26, having a two-part trunnion portion 28 at one end embracing the end of the cradle, has its opposite end pivoted 'at 29 to the upper end of an upright'member 30. The latter has its lower end pivoted at 3l to the base portion 32 of the casing `22. Coiled springs 34 and 36 on the right and left sides, respectively, of the upright member engage seats 38 and 40, respectively, formed in said member. The opposite end of v`A lock nut 41 on the end of member 44 locks the latter in position. Pivoted at 50 to the member 46 is an arm 5| having a yoke portion 52 at one end and having its opposite end pivotally connected at 53 to one end of a generally horizontally disposed rodv 54. The yoke portion surrounds a cylinder 56, which preferably is an air cylinder, and is pivotally connected at 58 thereto. Piston 59 in the air cylinder is connected by rod 60 and pin 62 to one end of an upright arm 64 pivoted at 66 to the base portion 32. The opposite end of arm 64 has a rack portion 68 engaging a sector gear 10. The sector gear has a locking portion 1I which engages a portion 12 of the upright member 30 to lock the upright against movement to the right duringthe crankshaft loading and drilling operations as shown in Figures 3, 4 and 5. Movement of the rack portion to the right, as

viewed in these figures, will pivotally move the l sector gear and locking portion thereof counterclockwise and allow the upright to beheld in a to the end of thecylinder,r the size of the open` ing being controlled by means of a screw threaded needle valve 82, as will be readily understood from Figure 3 of the drawings. der constitute a dash pot for damping movement of the upright when the cradle is in unlocked position.

As viewed in Figure 3. the left hand end of the The piston and cylincoiled spring 36 engages a seat86 formed on one end of a stem 86 having a threaded portion 8l on the opposite end thereof. 'I'he threaded portion of the stem is screwed into the upper end of an arm 88 and is secured in position by means of a lock nut 89. By means of the described construction the lock nut may be loosened and the stem and seat rotated to a new position to vary the tension of the coil spring, whereupon the lock nut may be tightened to maintain the adjustment. 'Ihe lower end of the arm 88 is keyed to a pivot pin 90. The latter is supported by raised portions 9| of the base 32. Also, keyed to the pin is another arm 92 pivotally connected at 93 with a coupling 94 having an internally threaded end portion 94'. A rod 95 has a knob 95 fixed to one end externally of the casing and a threaded end portion 96 engaging the'threaded portion 94'. Spaced collars'9l fixed to rod 95 engage on either side of an upright 98'. The rod is thus fixed against movement in` an axial direction and rotation of the rod by means of the knob 95' will move members 94 and 92 to further vary the length of the coil spring 36.

A cylindrical extension 96 of the lower part of the trunnion 28 has a coil spring 91 surrounding the same, one end of which engages an annular groove 98 formed in the lower surface of the 1 trunnion and the other end of which engages a collar 99. The collar is adjustable to vary'the compression of the coil spring by means of threaded collar membersr |00 and |02. The threaded collar members engage a threaded tubular extension |04 of an upright member |06 secured to the base by means of the nut |08. Within the cylindrical extension' 96 is a piston ||0 connected by means of rod 2 and universal joint |3 to a second rod ||4 extending through the upright member |06 and secured thereto 'by a nut I I5. A groove ||6 formed in the trunnion above the piston has an -adjustable needle valve ||8 extending therein to control fiowof air into and out of the cylinder above the piston. The cylinder and piston constitutes a dash pot for damping movement of the cradle.

Theopposite end of rod 54 is pivotally connected at |20 to an upright arm |22 pivotally connected at |24 to the base portion 32 of the casing. A coil spring |26, mounted between the 4base of the machine and an extension |28 of the upright, tends to move the upright |22 :about the pivot |24 toward an adjustable limiting stop |25. Near the upper end of the arm |22 is a generally frusto-conical hollowed,l out portion |30 adapted to cooperate with a generally frustoconical projection |32 formed on the trunnion. The air cylinder 56 is adapted to move the rod 54 to lock the trunnion in place during the operation of loading a crankshaft into the machine and during the drilling operation. The supporting mechanism for the opposite end of the cradle is similar to that just described and the description of the mechanism given will suflice for both. For simplicity of description the two knob members have been shown, one at each casing 22 and 24. If desired, for convenience of the operator of the machine, both may be mounted in the left hand casing 2,2 and an extension leading to the other cradle end provided. It will be understood that the supporting mechanism comprises resilient supporting means for the two opposite cradle ends during the operation of determining the mass center and means for locking thev ends against movement during the operation of loading the crankshaft forging, or other article. 1t will be appreciated that the crankshaft forging may weigh as much as pounds, or

Indicating means and' operating means therefor Since the cradle is substantially perfectly balanced to begin with, any unbalance shown on the indicator chart will be due to unbalance of the crankshaft forging. Rotation of the cradle with the crankshaft therein will cause the two to assume a position determined by the amount and direction, or plane, of the unbalance in the shaft. The flexibly mounted upright member 30 has fixed to a point at the top thereof an arm |34, see Figures 2 and 3, which is adapted to move a pivoted shaft |36 having a mirror |38 fixed thereto. A suitable coil, or other, spring A39 is adapted to bear against a portion of the shaft to force the'same against the end of the arm |34. It will be seen, therefore, that as the flexibly mounted upright 30 assumes a position determined by the unbalance of the crankshaft within the cradle it will move the arm |34, which in turn will rotate the shaft having the mirror fixed thereto against the compression of spring |39.` The greater the movement of the upright, which increases with the degree of unbalance, the greater the tilting movement of mirror |38. Light rays from a lamp bulb |40, see Figures 3 and 6, are adapted to strike the mirror and be reflected against a rapidly revolving mirror |42, which in turn projects the rays against a screen 0 to indicate the amount and direction of unbalance at one end of the shaft.

Ihe means for determining the unbalance at the right hand flexible support, as viewed in Figure 2, is generally similar to that just described. In order for the readings to be made for the two ends at the same point, a member |44 is secured to the right hand upright 30, as viewed in Figure 2, to be moved therewith through an arc as determined by the amount of unbalance. A tubular member |46 is secured to one end of the member I 44 by means of a clamping means |48. Thus, movement of the member 44 will cause the tubular member |46 to move therewith. At the left hand end of the tube |46, adjacent the left hand casing, or housing, is an upright tubular member |50, to the upper end of which is secured an arm |52 adapted to operate a tiltable mirror |54 against a spring |56. The operation of the mirror |54 is generally similar to that of mirror |38 and the description of mirror |38 will suflice for both. Adjacent the upright tube |50 is a-bearing support, generally indicated at |58, for tube |46. The indicating means is generally similar to that described in my Patent 1,761,945, dated June 3, 1930. vAny other suitable indicating means may be used, if desired.

Cradle mechanism l ure 18, having arcuate openings |68 in the upper end thereof on which the crankshaft may rest during loading and unloading fromthe cradle. It will be understood that the openings |68 are of such depth as not to interfere with the movement of the crankshaft during movement of the 5 same in determining the mass center; At substantially the central portion of the frame of the cradle are hardened members within which a movable means |12 is adapted to slide to locate the crankshaft axially before the cradle is rotated to determine the mass center of the crankshaft. Member |12 will bewithdrawn after the shaft is properly located in an axial direction and before the cradle is rotated.

Fixed to the frame of the cradle adjacent each end thereof are two motors adapted to drive positioning rollers |14 which move the crankshaft within the cradle while the cradle is being roftated. The motors are generally similar and are indicated at 6 in the drawings, see Figures l, 15 and 16. At each end of the cradle, vertically adjacent the positioning rollers, is a member |16 hinged at |18 to a portion of the cradle frame at one end and secured by means of a siidable locking bolt |80 to a projection |82 of the motor housing. It will be understood that the bolt |80 may be moved in an axial direction so that the hinged members may be thrown back while the crankshafts are being' placed and removed from the cradle. Mounted in two openings |84 formed, in each hinged member are two threaded rod members |86 having rollers |88 rotatably mounted at the lower ends thereof. Surrounding a portion of each rod member is a coil springA |90 adapted to force the rod and roller carried thereby in a direction generally radially toward the center of the cradle. Located in a vertical direction in each hinged member is a screw threaded adjustable stop member |92. By providing coil springs |90 of suitable stiffness the 40 members |92 may be omitted, if desired. Suita. ble supporting plates |94, see Figure 16, may be provided, if desired, to more rigidly connect the motor frames at each end of the cradle.

The means whereby the positioning rollers |14 45 may be driven by the four motors will now be described. The drive fromy each of the four motors is the same and a description of one will serve as a description for the others. Referring especially to Figures 19, 20 and 21, a pinion |96 fixed tothe motor shaft meshes With a gear |98 having a larger number of teeth than the pinion |96. Fixed tol the shaft 200 on which the gear |98 is fixed .and adapted to be driven therewith is a pinion 202 which in turn drives a gear 204 55 fixed to a shaft 206 to which is also fixed a pinion 208. The latter drives a gear 2|0 xed to a shaft2l2. Gear 2|0 drives a gear 2|3 secured to a shaft 2|4. A pinion 2|5 fixed to the shaft 2|4 drives a gear 2|1 xed to a shaft 2|6 sup- 60 ported by bearings 2|8 .at either end thereof. Substantially midway of the shaft between the bearings is a gear 220 keyed to said shaft which drives a gear 222 secured to shaft 224. V

One end of the latter has a threaded bore 225 65 within which is the threaded end 226 of a supporting shaft 221. The opposite end of the shaft 221 has an enlarged portion 228' slidable in a bore 230 formed in a xed frame member 23|. A positioning roller |14-is rotatably mounted by 70 a pin 232 in the enlarged portion of the shaft 221. The roller |14 is larger than the bore 230 and slides within a slot 233 formed in the member 23|, thus permitting the shaft 221 to move axially within the bore while preventing the shaft from 75 rotating. A suitable ball .type thrust bearing 234,

supported by means of anadjusting screw 236, is

mounted within a conical opening 236 in the end of the shaft 224., Between the enlargement 228 and the end of the shaft 224 is a rubber packing ring 228. Thegearing described above is adapted to reduce the speed of rotation of shaft 224 an appreciable amount as compared with that of a driving motor. Since shaft 221 is held against rotation, the rotation of shaft 224 will cause the screw threads on the latter to move the shaft 221 in an axial direction. The roller |14 carried thereby contacts the end of the crankshaft and moves it with respect to the cradle. The four motors are each reversible and hence the positioning rollers may be moved in either direction. The circuits to the-several motors will be fully described in connection with the description of the electrical controls. The several motors, positioning rollers, driving means therefor, hinged members and rollers mounted therein constitute parts of the substantially Iperfectly balanced cradle unit.

Cradle rotatingl means 'keyed thereto as seen in Figure 11. 'I'he 'opposite'end 254 of the shaft 252 is rotatably supported by means of a ball bearing 256, while the sleeve `portion is supported by means of another ball bearing 258. Keyed to the shaft is a Worm 260 in mesh with a worm gear 262. The latter is keyed to a tubular shaft 264 supported adjacent its ends by means of ball bearings 266 and 268. A handwheel 210 is keyed to the shaft 264 at the end adjacent the left hand cradle end as viewed in Figure 1. By means of a universal joint 212, sleeve member 214 and universal joint 213, the handwheel and sleeve are ljoined to the left hand end of the cradle to impart rotation thereto from the motor shaft 250.

In addition -to supplying the -power for rotating the cradle, the motor 5 also causes rotation of the revolving mirror of the indicating means which throws the beam of light onto the chart. Re-

- 284 at right angles to the shaft 216. At its opposite end the shaft 284 has a gear .286 keyed thereto which engages angear 288 keyed to a vertically extending shaft 289 which is connected by suitable gearing to the mechanism for revolving the mirror. Suitable ball bearings 290 adjacent either end of shaft 284 rotatably support the same. Bearings 292 and 294 adjacent the gear 288 support the end of the shaft 289 for rotation while a ball bearing 296 ina conical opening 298 in the end of the shaft resists end thrust on said shaft.

Referring to Figures 11 and 12, it will be seen that gear 218 engages a gear 300 fixed near one end of a shaft 302. The latter is mounted for rotation in a hollow frame 304 by means of suitable bearings 306. The shaft has secured to the upper endvportion thereof, as viewed in Figure 12, a 

